Basal till fabric and deposition at Burroughs Glacier, Glacier Bay, Alaska

Ham, Nelson R.; Mickelson, David M.

doi:10.1130/0016-7606(1994)106<1552:btfada>2.3.co;2

Cited by 52 publications

(26 citation statements)

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“…Various terms and classification systems have been applied to glacigenic sediments (Lawson, 1981;Dreimanis, 1989;Ham and Mickelson, 1994;Hart, 1994). Dowdeswell and Sharp (1986) distinguish four main types of sedimentary facies near modern terrestrial glaciers: basal melt-out till, deformed and undeformed lodgement till, sediment flows, and ice slope colluvium.…”

Section: Criteria For Identification Of Glacigenic Sedimentsmentioning

confidence: 99%

“…Lodgement till fabrics show a slightly greater dispersion around the mean V 1 axis than melt-out till (Dowdeswell et al, 1985). Whereas Mark (1973) asserts that a-b planes usually dip upglacier, Ham and Mickelson (1994) note that pebble imbrication in basal till may be oriented both up and down in the direction of glacier flow. Lawson (1979) also asserts that pebble imbrication does not necessarily indicate the direction of glacier flow for the same reason.…”

Section: Criteria For Identification Of Glacigenic Sedimentsmentioning

confidence: 99%

“…3). In contrast, Ham and Mickelson (1994) examined pebble fabrics of 27 samples near the Burroughs Glacier, Alaska, concluding that all are "basal tills" produced by progressive stagnation of debris-rich ice beneath a moving glacier during deglaciation.…”

Section: Diagrammes De Projection éQuiva-lente De Schmidt De Différenmentioning

confidence: 99%

“…Plot of S 1 and S 3 eigenvalues for diamict/paleosol units on Cloudy and Milk River ridges as compared to average values for meltout till, undeformed lodgement till, deformed lodgement till, glacigenic sediment flows (Dowdeswell and Sharp, 1986) and basal till (Ham and Mickelson, 1994 (Dowdeswell and Sharp, 1986), ainsi que du till de fond (Ham and Mickelson, 1994). fabric (Fig.…”

Section: Milk River Ridge Diamictonsmentioning

confidence: 99%

“…Average pebble dip (17°) is typical of deformed lodgement till. A third fabric sample taken for the entire section is also indicative of undeformed lodgement or basal till (Ham and Mickelson, 1994), with S 1 and S 3 values of 0.655 and 0.060, respectively. Mean pebble dip 13°, predominantly toward the S and SW) and azimuth of this sample suggest glacier flow was either from south to north or from north to south.…”

Section: Cloudy Ridge Diamictonmentioning

confidence: 99%

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Fabric, paleomagnetism, and interpretation of pre-illinoian diamictons and paleosols on Cloudy Ridge and Milk River Ridge, Alberta and Montana

Karlstrom

Barendregt

2004

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Pebble fabrics and sedimentological properties indicate that pre-Wisconsinan diamictons (Kennedy Drift) on Cloudy Ridge (Alberta) and Milk River Ridge (Montana) are of glacial rather than colluvial origin. S1 and S3 eigenvalues of the upper units on the two ridges are typical of undeformed lodgement till whereas those of the lower unit on Milk River Ridge are typical of glacigenic sediment flow. Other properties, including compact matrices, striations on stones, mean pebble dip angles, and Schmidt equal-area stereonet patterns, suggest each unit is lodgement or basal till. Pedogenic features indicate weathering zones capping the tills are paleosols. Degree of rubification, clay, iron and aluminum buildup, and clay mineral alteration resembles those of very strongly developed soils formed in warmer and moister environments. The argument that “soil-like features” of the Cloudy Ridge unit resulted from post-burial diagenesis is disproven because nearly identical paleosols occur at the surface on Milk River Ridge and other interfluves to the south. Each unit examined has normal polarity. Based on comparisons with similar till/paleosol sequences exposed in Kennedy Drift sections on nearby interfluves, the Cloudy Ridge till and the upper till on Milk River Ridge were probably deposited during the early to middle Bruhnes Normal Chron (780 ka to present) whereas the lower till on Milk River Ridge is of earlier Brunhes age or dates back to the Olduvai (1.98 to 1.76 Ma) Normal Subchron or the Gauss Normal Chron (3.6 to 2.6 Ma).

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Section: Criteria For Identification Of Glacigenic Sedimentsmentioning

confidence: 99%

Section: Criteria For Identification Of Glacigenic Sedimentsmentioning

confidence: 99%

Section: Diagrammes De Projection éQuiva-lente De Schmidt De Différenmentioning

confidence: 99%

Section: Milk River Ridge Diamictonsmentioning

confidence: 99%

Section: Cloudy Ridge Diamictonmentioning

confidence: 99%

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Fabric, paleomagnetism, and interpretation of pre-illinoian diamictons and paleosols on Cloudy Ridge and Milk River Ridge, Alberta and Montana

Karlstrom

Barendregt

2004

gpq

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Glacigenic clast fabrics: genetic fingerprint or wishful thinking?

et al. 1999

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The interpretation of glacigenic diamictons is a subjective process, for which quantitative support is frequently sought from parameters such as clast shape and fabric. It has been widely suggested that different glacigenic diamicton facies possess distinct clast‐fabric signatures. This paper examines this concept using a data set of 111 clast fabrics, and a synthesis of published results. Eigenvalues are calculated and compared for a variety sedimentary facies. It is concluded that clast fabric alone is not able to discriminate between different glacigenic facies, and it is argued that clast fabric offers little quantitative support in the interpretation of glacigenic sediments. It is suggested, therefore, that although clast fabric may continue to have a role as an indicator of relative strain at specific sites, its use in the discrimination of glacigenic facies is limited. Consequently, we should be much more selective in undertaking such analyses in the future. Copyright © 1999 John Wiley & Sons, Ltd.

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2006

Glacier Science and Environmental Change

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Basal till fabric and deposition at Burroughs Glacier, Glacier Bay, Alaska

Cited by 52 publications

References 0 publications

Fabric, paleomagnetism, and interpretation of pre-illinoian diamictons and paleosols on Cloudy Ridge and Milk River Ridge, Alberta and Montana

Fabric, paleomagnetism, and interpretation of pre-illinoian diamictons and paleosols on Cloudy Ridge and Milk River Ridge, Alberta and Montana

Glacigenic clast fabrics: genetic fingerprint or wishful thinking?

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